It is well known in the art to carry out certain semiconductor and manufacturing operations under conditions of high or moderate vacuum. One of the conventional processes in carrying out such operations is to introduce a reagent vapor into the vacuum system where the vapor reacts with the semiconductor devices undergoing treatment or preparation. It is extremely important, in many of these operations, that the rate of reagent vapor flow into the vacuum system, and consequently, the rate of reaction of the reagent vapor with the semiconductor surface be very precisely controlled.
A number of methods of introduction of reagents into vacuum furnaces and other vacuum semiconductor manufacturing systems are known. Most of the systems are very difficult to operate under conditions which will assure that aerosol of the reagent is formed, and to assure also that mass flow rate is accurate and repeatable. One feature of this invention resides in the provision of a critical orifice system for introducing vapor into such vacuum systems accurately with no risk of aerosol formation.
Systems are well known for providing reagents in reservoirs or bubblers and for maintaining the temperature of reservoir or bubbler as desired to obtain the desired vapor pressure. One such system is sold by J. C. Schumacher Company identified as the STC or Source Temperature Controller. The STC is, in brief description, an enclosure for the reservoir and heating means and controlling means for very precisely maintaining the temperature of the reservoir.
Systems are well known for providing a precisely controlled mass flow of inert gas, e.g. nitrogen. One such system is sold by the J. C. Schumacher Company as the MFC or Mass Flow Controller. The MFC includes inlet and outlet valves and an orifice control device and flow meter.